This invention relates to vibration compacting machines, and more particularly to an eccentric assembly for a vibration compacting machine.
Vibration compacting machines are used in leveling paved or unpaved ground surfaces. A typical vibration compacting machine includes an eccentric assembly for generating vibrations that are transferred to a drum assembly of the compacting machine. The eccentric assembly commonly includes one or more eccentric weights that are adjustable between a plurality of discrete radial positions relative to a shaft in order to vary the amplitude of the vibrations that are generated by rotating the eccentric weight(s) about the shaft.
One such device includes a plurality of eccentric weights that are fixed to the shaft and a corresponding number of counterweights that are coupled to the opposite side of the shaft relative to the eccentric weights. The counterweights are moveable between a retracted position and a projected position relative to the longitudinal axis of the shaft. When the counterweights are in the retracted position their effect on the eccentric weights is minimized, resulting in maximum vibration amplitude being generated by the eccentric weights. The counterweights are normally biased toward the retracted position, however as the shaft rotates the biasing force is overcome and the counterweights are moved to the projected position where the counterweights are further away from the shaft. As the counterweights move further from the shaft, the counterweights reduce the effect of the eccentric weights resulting in a lower vibration amplitude.
One type of adjustable eccentric assembly operates by varying the rotational speed of the shaft. The eccentric assembly includes one or more eccentric weights that are biased toward the shaft. During operation of the eccentric assembly the shaft rotates, and as the rotational speed of the shaft increases, a centrifugal force overcomes the biasing force and causes the eccentric weight to move away from the shaft. The vibration amplitude increases as the eccentric weights move away from the shaft.
The present invention is directed to an eccentric assembly for a vibration compacting machine. Rotating the eccentric assembly generates vibrations that are transferred to the drum assembly of the vibration compacting machine.
The eccentric assembly of the present invention generates vibrations that have a lower amplitude at high rotational speeds (i.e., frequencies). Reducing vibration amplitude at higher shaft speeds minimizes wear to each of the load bearing components in the vibration compacting machine, resulting in an extended service life for the vibration compacting machine. The eccentric assembly of the present invention is also easily and inexpensively manufactured, can be readily adapted to be used in existing vibration compacting machines and encases all critical moving components within a protective tubular section.
The eccentric assembly includes a tubular section, an eccentric weight, and a counterweight. The eccentric weight is mounted within the tubular section such that as a motor rotates the eccentric assembly, the eccentric weight generates vibrations that are transferred to the drum assembly of the vibration compacting machine. The eccentric assembly also includes a counterweight that is slidably coupled to the eccentric weight. The counterweight moves over a range between a first position where the counterweight contacts the eccentric weight and a second position where the counterweight contacts the tubular section.
During operation of the vibration compacting machine, the eccentric assembly generates a maximum moment of eccentricity about an axis of rotation when the counterweight is in contact with the eccentric weight (i.e., the first position). As the rotational speed of the eccentric assembly increases, the eccentric weight and the counterweight are separated and the moment of eccentricity generated by the rotating eccentric assembly decreases.
The counterweight is preferably biased toward the first position by a spring. The counterweight will remain in the first position until the eccentric assembly is rotated at a sufficient speed to create a centrifugal force on the counterweight that overcomes the biasing force generated by the spring. Once the centrifugal force is larger than the biasing force, the counterweight moves toward the second position, thereby lowering the moment of eccentricity and decreasing the vibration amplitude.
Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims, and drawings.